Doc: fix typos for v3benchmark
Doc: fix typos for v3benchmark

The official benchmakr code seems to be in `tools` directory (not in `hack`).

sinsharat/etcd,insequent/etcd,nekto0n/etcd,qqsun8819/etcd,mqliang/etcd,bluebreezecf/etcd,mqliang/etcd,akauppi/etcd,ajityagaty/etcd,dannysauer/etcd,linuxcer/etcd,fasaxc/etcd,zaphod-concur/etcd,luxas/etcd,zaphod-concur/etcd,joshix/etcd,siddontang/etcd,rnaveiras/etcd,visheshnp/etcd,handsomesun/etcd,sayden/etcd,mqliang/etcd,purpleidea/etcd,tamird/etcd,plasticbox/etcd,visheshnp/etcd,StorReduce/etcd,sebrandon1/etcd,a-robinson/etcd,fasaxc/etcd,gyuho/etcd,cockroachdb/etcd,CrazyJvm/etcd,wantonsolutions/dinv-etcd,shawnps/etcd,etcd-io/etcd,armstrongli/etcd,whuwxl/etcd,fanminshi/etcd,jlamillan/etcd,bluebreezecf/etcd,YuleiXiao/etcd,westhood/etcd,Timer/etcd,glevand/coreos--etcd,chipironcin/etcd,ravigadde/etcd,sebrandon1/etcd,OyTao/etcd_learning,cockroachdb/etcd,handsomesun/etcd,hongchaodeng/etcd,coreos/etcd,ktateish/etcd,etcd-io/etcd,raoofm/etcd,mkumatag/etcd,vimalk78/etcd,endocode/etcd,Timer/etcd,sinsharat/etcd,shawnps/etcd,HideoYamauchi/etcd,etcd-io/etcd,StorReduce/etcd,swingbach/etcd,fanminshi/etcd,xiang90/etcd,sofuture/etcd,ajityagaty/etcd,rchicoli/etcd,luxas/etcd,westhood/etcd,YuleiXiao/etcd,sayden/etcd,rnaveiras/etcd,glycerine/etcd,coreos/etcd,OyTao/etcd_learning,mkumatag/etcd,dnaeon/etcd,xiang90/etcd,oscarrr110/etcd,mkumatag/etcd,jonboulle/etcd,ajityagaty/etcd,yudai/etcd,siddontang/etcd,whuwxl/etcd,heyitsanthony/etcd,plasticbox/etcd,glevand/coreos--etcd,jonboulle/etcd,rnaveiras/etcd,joshix/etcd,rchicoli/etcd,gyuho/etcd,ktateish/etcd,a-robinson/etcd,hongchaodeng/etcd,oscarrr110/etcd,li-ang/etcd,jlamillan/etcd,swingbach/etcd,ravigadde/etcd,wantonsolutions/dinv-etcd,qqsun8819/etcd,wantonsolutions/dinv-etcd,dnaeon/etcd,nekto0n/etcd,CrazyJvm/etcd,lorneli/etcd,dannysauer/etcd,achanda/etcd,armstrongli/etcd,heyitsanthony/etcd,purpleidea/etcd,tguangch/etcd,li-ang/etcd,vimalk78/etcd,sofuture/etcd,tguangch/etcd,mickep76/etcd,raoofm/etcd,lumjjb/etcd,cchamplin/etcd,bdarnell/etcd,achanda/etcd,endocode/etcd,insequent/etcd,bdarnell/etcd,fasaxc/etcd,linuxcer/etcd,akauppi/etcd,tamird/etcd,lorneli/etcd,cchamplin/etcd,yudai/etcd,chipironcin/etcd,mickep76/etcd,lumjjb/etcd,HideoYamauchi/etcd,glycerine/etcd